Which layer of the hair is the outermost protective layer?

The cuticle is indeed the outermost protective layer of the hair. It consists of overlapping, scale-like cells that create a barrier against environmental damage and moisture loss. This protective layer plays a crucial role in maintaining the integrity and health of the hair.

When the cuticle is intact and lying flat, it helps the hair to reflect light beautifully, contributing to shine and smoothness. Damage to the cuticle can result in a rough texture, dullness, and increased susceptibility to breakage and other forms of harm.

In contrast, the cortex, which is the middle layer of the hair, contains the majority of the hair’s mass and is responsible for strength and color. The medulla is the innermost layer, which may be absent in some hair types and generally has a lesser impact on the overall health and appearance of the hair. The term "stem" typically does not refer to a specific layer within the hair strand in hair anatomy. Thus, the cuticle stands out as the essential barrier responsible for protecting the hair from both physical and environmental damage.